Transmission



Oct. 7, 1941. D. s. BENNETCH wmmsmssrou Filed Sept. 12; 1936 17 Sheets-Sheet 2 INVENTOR David 5. Ben'neZ'Zz/z, BY

ATTORNEY D. S. BENNETCH Oct. 7, 1941.

TRANSMISS ION l7 Sheets-Sheet 3 .Filed Sept. 12, 1936 Oct. 7, 1941. D. s. BENNETCH 2,257,724

TRANSMISS ION Filed Sept; 12, 1936 17 Sheets-Sheet 5 XNVENTOR David .5 fle/mela/z,

ATTORNEY .Oct. 7, 1941. o. s. BENNETCH TRANSMISS ION Filed Sept. 12, 1936 17 Sheets-Sheet 7 INVENTOR Dar/d 6T Ben/2127M, M

ATTORNEY Oct. 7, 1941. o. s. BENNETCH TRANSMIS S ION Filed Sept. 12, 1956 17 Sheets-Sheet a INVENTOR Da V/H 5 Ben/2875A, BY

MM 2,. M ATTORNEY NNM Oct. 7, 1941. D; s H 2,257,724

TRANSMISSION Filed Sept. 12, 1936 17 Sheets-Sheet 9 ATTORNEY Oct. 7, 1941.

D. s. BENNETCH TRANSMIS S ION Filed Sept. 12, 1936 1'7 Sheets-Sheet 11 INVENTOR Dav/d 6. BenneZ c/I, B

ATTORN EY Oct. 7, 1941. n. s. BENNETCH TRANSMISSION Filed Sept. 12, 1936 17 Sheets-Sheet l2 R n Y m E N m E z 0 v T J M W Y 1941- D. s. BENNETCH 2,257,724

TRANSMISSION Filed Sept. 12, 1936 1'? SheetsSheet l4 MVN Oct. 7, 1941. D. $.BENNETCH TRANSMISS ION Filed Sept. l2, 1956 17 Sheets-Sheet l5 QQuQQBFSH Maw WM 3 Q.

. Rival 5E5 Q 4.3mm mmmw Y, INVENTOR David .5. Bennefciz, 2%,, M ATTORNEY mm RM Oct. 7, 1941. D. s. BENNETCH 2,257,724

TRANSMISSION Filed Sept. 12, 1936 17 Sheets-Sheet 1'! o V A !NVENTOR Band 5 BenneZc/z,

ATTORNEY meme e. 7, 1941 UNITED STATES PATENT OFFICE swun 28:31:31, 33; 100.400

13 Claims.

The invention relates to speed transmissions for automotive vehicles or the like and, more particularly, to a fully automatic control for such transmissions. I

In the preferred form, the invention utilizes a variable speed hydraulic transmission comprising a variable stroke pump unit driving a similar, variable stroke motor unit, the pump unit being driven by a prime mover, such as the ordinary automobile engine and the motor unit driving the load, such as the rear wheels of such automobile. Each unit may comprise a rotary -cylinder block having a plurality of axially extending cylinders cooperating with a tiltable swash plate, the tilting of which varies the stroke of the pistons between zero and maximum. A suitable mechanical clutch may be provided for providing direct drive at which time the hydraulic transmission may be effectively cut out of operation.

In the preferred form, arrangement is made for fully automatically controlling the transmission, i. e. after the automotive engine is started, it is only necessary to depress the forward pedal, corresponding to the ordinaryaccelerator pedal, for complete operation at all speeds in a forward direction, the amount of speed being determined by the amount by which the forward pedal is depressed. If desired, a separate brake pedal may be provided, and a separate reverse pedal for backing up the vehicle, this profails, a suitable emergency starter may be provided, including an electric motor for driving the transmission supercharger ordinarily used for overcoming foaming. A suitable overriding clutch system may be provided for permitting the supercharger to be driven by either the electric motor or by the drive shaft of the transmission without interference.

If desired, arrangement may be made for moving the pump and motor blocks of the transmission away from the stator when the hydraulic transmission is not in operation. This may be done simply by providing an annular pressure space communicating with the cylinders, which operates to force the pump and motor blocks against the stator when there is any pressure in the cylinders, allowing the pump and motor blocks to retract when pressure in the cylinders viding threepedal control. If desired, control by the brake pedal may be eliminated by a suitable hand operated change over device for changing over to two pedal control. In the two pedal control, the forward pedal and the reverse pedal operate in the same manner as with the three pedal control, except that, with the two pedal control, permitting the pedal to rise above a predetermined point operates to apply the brakes. For full automatic control, the tilting of the swash plates and the operation of the mechanical clutch may be governed by a system of governors, one of which may be responsive to engine speed, another to torque exerted by the rear wheels, and the third to the inclination or grade on which the vehicle is moving. These controls insure smooth automatic operation under all conditions.

If desired, a pressure tank may be provided is relieved. Provision may be made for using the transmission as a brake, a special regulating valve being provided in the suction side of the stator under control of the brake pedal for regulating the amount of back pressure to the braking action desired.

For controlling the supercharger pressure, a variable pressure relief valve may be provided whose operating pressure varies with the tilt of the forward swash plate. The greater the tilt of this swash plate the higher the pressure generated by the supercharger.

The invention also consists in certain new and original features of construction and combinations of parts hereinafter set forth and claimed.

Although the novel features which are believed to be characteristic of this invention will be particularly pointed out in the claims appended hereto, the invention itself, as to its ob- Jects and advantages, and the manner in which it may be carried out. may be better understood by referring to the following description taken in connection with the accompanying drawings forming a part thereof, in which Fig. 1 is a diagrammatic view of an automobile with the transmission and controls embodied therein;

Fig. 2 is a side elevation of the transmission showing the several manual controls;

Fig. 3 is a front view of the transmission taken on the line 3-4 of Fig. 4;

Fig. 4 is a vertical section through the transmission;

Fig. 5 is a transverse section on the line 5-5 of Fig. 4;

Fig. 6 is a transverse section through the stator taken on the line 0-0 of Fig. 4;

part of this '7 is a section taken on the line IL-l of Fig. 12;

Fig. 8 is a section through the master control taken on the line 8-8 of Fig. '7;

Fig. 9 is a section taken on the line 9-9 of 8; Fig. 10 is a back view of the master control mechanism;

Fig. 11 is a detail illustrating the pressure regulator taken on the line Ii-Il of Fig. 6;

Fig. 12 is a vertical section through the transmission illustrating the master control interlocking device and trunnion control; I

Fig. 13 is a vertical section through the transmission illustrating the automatic torque control; pendulum control; pressure release for starting and variable pressure relief valve;

Fig. 14 is a section through the pedal mounting taken on the line M-M of Fig. 12;

Fig. 15 is a detail of the pedal control taken on the line l5-|5 of Fig. 14;

Fig. 16 is a section on the line I6--I 6 of Fig. 15;

Fig. 17 is a detail of the brake cam;

Fig. 18 is a detail of the reverse cam;

Fig. 19 is a section on the line l9i9 of Fig. 13 showing the pendulum'control; I

Fig. 20 is a section on the line 20--20 of Fig. 13;

Fig. 21 is a section through the supercharger and driving mechanism;

Fig. 22 is a section of the overriding clutch taken on the'line 2222 of Fig. 21;

Fig. 23 is a detail of the overriding clutch;

Fig. 24 is a vertical section through the trunnion control illustrating one position of the trunnion control valve;

Figs. 25 and 26 are'similar sections of Fig. 24, but illustrating other positions or the trunnion control valve;

Fig. 27 is a section on the line 21-41 of Fig. 24;

Fig. 28 is an end view of the trunnion control;

Fig. 29 is a section through the interlock taken on the line 29-49 01' Fig. 12;

Figs. 30-35 illustrate diagrammatically the various positions of the trunnions for various conditions of operation;

Fig. 36 is a diagrammatic view with some parts greatly exaggerated, illustrating the main hydraulic connections between the several pieces of apparatus, and illustrating the starting or cranking operation;

Fig. 36A is a diagrammatic view similar to Fig. 36, illustrating the backing operation or reverse drive; v

Fig. 36B is a diagrammatic view similar to Fig. 36, illustrating forward drive;

Fig. 37 is a detail, partly in section, illustrating a coordinating device for insuring smoothness of operation;

Fig. 38 is a section on the line 38-30 of Fig. 39 is a perspective of the slide valve of the coordinating device; and

Fig. 40 illustrates the hydraulichook up between the coordinating device, 'the stator, and the pressure regulator.

In the following description and in the claims, various details will be identified by specific names for convenience, but they are intended to be as generic. in their application as'the art will permit. 7

Like reference characters denote like parts in the several figures of the drawings.

In the drawings accompanying and forming specification, certain specific disvention.

closure of the invention is made for purposes of explanation, but it will be understood that the details may be modified in various respects without departure from the broad aspect of the in- General Referring now to the drawings and, more particularly, to Fig. l, the invention is shown as applied to a modern automobile. However, it will be understood that theinvention may be applied to any installation requiring variable speed transmission, such as, for example, heavy duty busses and trucks. and Diesel railway locomotives and the like. In Fig. 1, the transmission is denoted, in general, by I, the ordinary internal combustion engine of the automobile by 2, and the rear end differential by 3. The transmission I is located in the space usually occupied by the clutch and sliding gear transmission of the conventional automobile. I

In'the form shown, the car is provided with four foot controls and two hand controls. The foot controls comprise brake 4, forward pedal 5, reverse pedal 6 and starter I. The hand controls comprise an emergency starter button 8 and a change over knob 9 for changing over the foot controls from three pedal control to two pedal control. The use and operation of the several controls will be described in due course.

If desired, the engine flywheel may be omitted, the mass of rotating parts of thetransmission serving the function of a flywheel.

Variable stroke transmission Referring now to Figs. 3-6, the transmission, in general, comprises a casing I having a body I2 and cover I3; a drive shaft I4 and a driven shaft I5; and a pump unit I6 and a motor unit I! having, respectively, the tiltable swash plate assemblies I9 and 20 to vary the stroke of the The drive shaft I 4 is shown in the form of a sleeve and is journalled in a ball bearing assembly 24 in the forward wall of the body I2 and in a ball bearing assembly 25 in stator I8. The drive shaft I4 is keyed to the forward support 26 to which the pump block is further keyed so as to rotate with support 26, but to move axially thereon for a purpose hereinafter described.

This transmission is of the same general type as that disclosed in application Serial No. 24,353,

filed May 31, 1935, now Patent No. 2,151,415 issued March 21, 1939, although differing somewhat in constructional features; The driven shaft I5 is keyed to the driven sleeve 2'! which is journalled'in bearing assembly .28 supported by the rear wall of the housing.

The sleeve 21 is also journalled in bearing assembly 29 supported by stator I8. Rear support 30 is keyed to sleeve 21 and has motor block I! further keyed thereto. I,

The mechanical clutch 2i comprises an adjustable block33 carrying a pair or pins 36 slidable longitudinally in slots in the drive sleeve M.

The clutch block 33 has dog teeth engaging similar dog teeth on afixed block 34 pinned to the drivenshaft II. The engagement of the mechanical clutch 2| is controlled by a sleeve 88 secured to the pins 88 and having an annular groove II in which ride bosses on yoke 81 (Fig. 3) pivoted on shaft 38. The yoke 81 is operated by a slotted cam 38 in which rides follower Ill (Fig. 4) secured to the yoke 31. Cam 88 is secured to shaft ll to which is secured arm 42 pivoted to rod 48 extending to the rear trunnion for a purpose later described.

The motor block I! has a plurality of cylinders 48 (six in number in the form shown) and the inner end of this block fits snugly against the end face of the stator II. An annular pressure space ll having a plurality of restricted ports 41, one

for each cylinder, is provided for between the rear support 38 and the motorblock l1, this space being sealed by rings N and 48. Thus, pressure in the cylinders is communicated to pressure space ll to firmly press the motor block l1 against the stator i8. When pressure is relieved in the cylinders it (as when the mechanical clutch 2! is engaged and the swash plates l8 and 28 are in erect position), the motor block l1 may move away from the stator i8 thus relieving the friction between block I! and stator l8 when no power is being transmitted between.

pump and motor blocks l8, l1.

Disposed within the cylinders 48 are pistons 48 having the usual piston rings. 48 may comprise a body and a removable head 88 forming therebetween a spherical socket for the ball II' on the end of hollow connecting rod 52. The connecting rod 82 is provided with an oil hole 83 which cooperates with an opening I in the piston head 58 for a purpose hereinafter dwcribed more in detail.

The rear or motor swash plate comprises a housing 85 having trunnions 56 (Fig. 5) seated in the casingbody l2, so that the swash plate may be tilted as desired. The housing 85 includes a bearing'plate 81 having an annular seat for a ball bearing assembly 58 comprising a plurality of balls separated by the usual spacer.

Rotatably mounted on the housing 58 is the swash ring 58 having an annular seat engaging the ball bearing assembly 58. The swash ring 89 also has an annular holding ring 884 riding over the bearing plate 51. It will be understood that in the ordinary operation of the transmission there is practically no engagement between the holding ring 8 and the bearing plate 51, all of the stress both axially and radially being withstood by the ball bearing assembly 58.

The swash ring 59 has. secured thereto a pair of bearings 64 in which are journalled a pair of outer studs 65 secured in ring 86. Ring 88 is journalled on a pair of inner studs 61 supported by driven sleeve 21. Thus ring 66 and sets of studs 85, 81 form, in eilect, a universal mounting for the swash ring 58 on driven sleeve 21, permitting the driven sleeve 21 to be driven by the swash ring 58 irrespective ofthe angle of tilt of swash housing 55. 7

To reduce friction between the connecting rods 52 and the swash ring 88, a floating connecting rod arrangement is provided. The swash ring 58 has a plurality of bearing bodies Gland removable caps 8|, one set for each cylinder. Each bearing body 80 and cap 81 forms a socket for a ball 88 secured to the end of a connecting rod 82 by a nut, -forming connecting rod bear- Each piston 1 total force exerted by the liquid between the swash ring 88 and the ball 88 is equal to the force exerted by the liquid on the piston 49. It will be noted that the projection area of the space occupied by the liquid between ball 68 and socket 88 on a plane perpendicular to the connecting rod axis is substantially equal to the area of the piston. Thus, mechanical stress exerted between the swash ring 59 and the connecting rods is reduced to a minimum, all of this stress being transmitted by liquid pressure transmitted from the liquid above the piston.

The construction of the pump unit, including the cylinder block it, swash plate 19, connecting rods, pistons and pressure space, is substantially the same as the corresponding parts relating to the motor unit and hence it is not necessary to describe these parts in detail. Similar parts have corresponding reference characters.

The stator l8 (Fig. 6) is supported by the easing body i 2 on ledges 18. The stator l8 isprovided with a pair of arcuate openings 1|, 12 which are arranged on the line of movement of the centers of the cylinders. A greater space than the diameter of the cylinder is provided between the adjoining ends of these openings.

Assuming that both swash plates are tilted as in Fig. 33', and the transmission is rotating in the direction of the arrow A (Fig. 5'), it will be seen that the pistons of the pump unit suck liquid as the cylinders move from the bottom of opening 1| to the top thereof. Thus, this opening in relation to the pump unit isa suction opening, the other opening 12 in relation to the pump unit being a discharge opening.

It will be understood by those skilled in the art that with both swash plates, for example, in full tilt position, the pump receives liquid from the motor through the suction opening 1|, compresses this liquid and discharges it through the discharge opening 12, thus driving the motor unit hydraulically. The oil travels through a closed path, never getting out in the casing of the transmission except for leakage or positive discharge.

Pedals Referring more particularly to Figs. 2, 3 and 14 to 18, the brake pedal 4, forward pedal 5 and reverse pedal 6 are concentrically mounted on the outside of the housing body l2 and are normally held in retracted position by a series of springs denoted by 88. The pedals l, 5 and i are mounted, respectively, on concentric shafts 14, 15 and 16, which carry, respectively, a brake cam 11, forward cam 18 and reverse cam 19. Brake cam 11 has an internal cam surface as illustrated in Fig. 17. Reverse cam 19 has an external cam surface and carries pin 94 as illustrated in Fig, 18. Forward cam 18 is similarin shape to reverse cam 19 and carries a pin 93. The effects of the shapes of these cams will be explained in due course.

Brake pedal 4 has an extension engaging with a lever 8! connected to shaft 82, which in turn supports arm 98 (Fig. 12) connected to piston l2| in brake cylinder 89. Arm 8| is connected to brake rod 382 (Fig. 2) extending to the ordinary mechanical brake linkage of the car. This construction represents a safety feature which permits straight mechanical operation of the car brakes by direct foot pressure in case the automatic braking feature fails.

The brake cam 11 cooperates with a roller or follower (Figs. 12, 15 and 16) on brake arm 

